Fw: [HOn3] Figuring Grades

Stephen Silver

John,  I tested a 4% grade with both of my Blackstone K27s.  Both pulled six unweighted BS cars (a mix of 6 different cars) and a caboose but only under some heavy throttle. Double heading they pulled 10.  I don't have a 4% grade but something much closer to 3% on one section of track.  We will see what happens in reality when it gets built.

Life is mostly attitude and timing

----- Forwarded Message -----

From: John Cytron <rgsjohnny@...>
To: "HOn3@groups.io" <HOn3@groups.io>
Sent: Thursday, September 26, 2019, 4:21:13 PM PDT
Subject: Re: [HOn3] Figuring Grades

I think you all have figured this incorrectly. Bob asked for the final elevation.

If the plan is ½” to the foot, then 8 inches on the plan is 16 actual feet. Think of each 1% grade as equal to 1/8th inch per foot in the real world.  (⅛” = 1/96th of a foot or slightly  more than 1%.) A 1% grade would rise 1/8th inch over 1 foot and 16 times that over 16 feet, or a rise of 16x1/8th which is 2 inches. Over 16 actual feet, the rise would be 16 times 1/8th or 2 inches. 

The calculations made by the earlier posters is correct to the scale of the drawing; that is, 0.32 inches.  So what is 0.32 inches to 0.50 inches, the scale of the drawing?. It is  0.32/0.50 or about 0.64. 0.64 is almost ⅔ and what is 2/3rds of a foot? —8 inches.  More precisely it is 0.64 times 12 inches per foot or 7.68 inches in the real world, that is, if the ½” to the foot plan were at full scale.

I still like to figure 1/8th rise in 1 foot as equal to 1%. It makes for easy figuring.

Anyway, why would you want a 4% grade as that is really rare even in narrow gauge (except for a few places like Baxter Pass on the Uintah RR and some others.Today's HOn3 locos could barely make that grade with 2 cars and a caboose.


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